1. Field of the Invention
The present invention relates to a portable terminal device, and a method and program for varying light illuminance used therein. In particular, the present invention relates to a method for varying the light illuminance in a camera function used in the portable terminal device.
2. Description of the Related Art
Recently, a portable terminal device has been made multifunctional, and the terminals with a musical reproduction function, a camera function or the like are commercially available. A user can take only underexposed images by a miniature camera used in the portable terminal device without a light function, and the thus obtained still or moving images may be dark in photography or picture phone.
Thus, the light is highly important as a photography auxiliary function in the portable terminal device. A flash lamp is fixedly or detachably attached to make flash photography possible (refer to, for example, Japanese Patent Laid-Open Publication No. 2002-374331 (pages 9 to 13 and FIG. 2)).
An extremely miniature camera is used in the portable terminal device as the camera function by reason of its structure. In shooting still or moving images by the miniature camera, the light has become highly important factor as a photography illumination function to make the images clearer. A white LED (Light Emitting Diode) or the like is used as an auxiliary light source for photography in the portable terminal device.
At present, the illuminance of the light of the portable terminal device for photography illumination is constant irrespective of distance from the device to an object to be photographed. There is the function of manually varying the illuminance in stages during photography in dark conditions, but the structure of the function is not related to the distance from the device to the object.
The majority of camera-equipped portable terminal devices used at present have a light for illumination at constant illuminance. Some portable terminal devices have an illuminance value variable light (for example, in five stages or the like). The illuminance value variable light, however, is assumed as an auxiliary function for photography in dark conditions, so that a user himself/herself has to decide and adjust the illuminance before or during photography.
Some of the conventional camera-equipped portable terminal devices described above further have a zoom function. In this case, however, the light as the photography auxiliary function does not have an (automatic) illuminance variable function which takes the distance from the device to the object into consideration.